UNIVERSITY   OF    CALIFORNIA        AGRICULTURAL  EXPERIMENT  STATION 


BENJ.   IDE   WHEELER,   President 
;ui  \j  n  c. 

BERKELEY 


COLLEGE   OF  AGRICULTURE 

THOMAS    FORSYTH    HUNT,  Dean  and  Director 


CIRCULAR  No.  132 

(June,  1915) 


WHEN  TO  VACCINATE  AGAINST 
HOG  CHOLERA 


This  station  advises  all  hog  owners  to  vaccinate  their  swine  against 
hog  cholera  as  soon  as  the  danger  of  exposure  is  suspected.  The  late 
summer  and  fall  is  the  time  when  hog  cholera  is  most  prevalent. 
Epidemics  have  already  started  in  several  places  in  the  state,  and  even 
in  localities  supposed  to  be  free  from  the  disease  farmers  are  warned 
to  keep  their  hogs  isolated  and  to  watch  for  signs  of  sickness. 

Hog  cholera  in  the  living  sick  animal  does  not  present  symptoms 
which  positively  distinguish  it  from  other  affections.  If  one  of  the 
hogs  gets  sick  it  should  be  removed  at  once  from  the  herd.  Before  it 
dies  a  veterinarian  should  be  called  to  kill  and  autopsy  the  animal 
and  take  temperatures  on  the  others.  This  will  usually  show  whether 
or  not  the  disease  is  cholera.  Do  not  wait  until  an  animal  dies,  for 
if  cholera  is  present  great  losses  will  result  from  its  spread  unless  the 
healthy  hogs  are  immunized  at  once. 

If  pigs  get  off  feed  or  show  any  sign  of  sickness  the  probability  of 
its  being  cholera  should  be  considered,  since  nine  out  of  ten  sick  hogs 
have  this  disease.  Recent  investigations  have  shown  that  most  of  the 
so-called  cases  of  swine  plague,  infectious  pneumonia,  contagious  sore 
eyes,  staggers,  and  oftentimes  paralysis,  are  really  hog  cholera,  and 
the  failure  to  recognize  the  underlying  cause  of  such  conditions  has 
resulted  in  much  unnecessary  loss. 

ADVICE  CONCERNING  VACCINATION 
Owing  to  the  expense  of  vaccination  and  the  danger  from  care- 
lessness in  the  use  of  virus,  this  station  recommends  the  immunization 
of  hogs  only  in  infected  localities,  except  in  case  of  valuable  swine 
which  are  to  be  shipped  for  exhibition  or  breeding  purposes.  There 
are  two  methods  of  immunizing  hogs  against  cholera.  In  one  the  serum 
alone  is  used,  producing  an  immunity  lasting  from  thirty  to  ninety 
days;  in  the  other,  a  small  amount  of  virus  (virulent  hog-cholera- 
producing  blood)  is  injected  simultaneously  with  the  serum,  but  at 
a  different  point  in  the  body  of  the  animal.  This  latter  is  known  as 
the  simultaneous  method  and  will  produce  lasting  immunity,  except 
in  suckling  pigs  and  small  shotes,  in  which  case  the  immunity  may 


disappear  as  they  mature.  Some  serum  manufacturers  and  others  in 
their  efforts  to  sell  serum  have  advised  air  hog  owners  to  immunize, 
stating  that  hog  cholera  is  so  prevalent  that  no  farmer  can  afford  to 
run  the  risk  of  keeping  a  susceptible  herd.  Under  California  con- 
ditions general  vaccination  at  present  would  be  desirable  only  in 
certain  badly  infected  districts,  while  in  other  localities  it  would  be 
a  needless  expense.  The  general  use  of  the  simultaneous  method  in 
non-infected  districts  may  spread  hog  cholera,  'although  we  have  seen 
no  evidence  that  it  has  ever  done  so,  while  the  use  of  serum  alone 
would  be  a  waste  of  money,  for  the  reason  that  the  immunity  from 
this  method  is  so  short. 

WHAT  METHOD  TO  USE 

There  is  often  a  difference  of  opinion  among  veterinarians  as  to 
when  to  use  the  serum  alone  and  when  virus  should  be  used  with  the 
serum.  As  previously  stated,  vaccination  is  not  advisable  unless  there 
appears  to  be  danger  of  cholera  infection. 

In  infected  herds  this  station  usually  advises  the  simultaneous 
method  on  all  healthy  hogs,  except  sows  heavy  with  pig  or  with  litters 
less  than  six  weeks  old.  Such  sows  and  their  litters  may  receive  serum 
alone,  but  should  be  re-immunized  with  serum  and  virus  six  to  ten 
weeks  after  farrowing.  Temperatures  should  always  be  taken  and  the 
animals  which  have  over  104°  F.  should  be  considered  already  infected 
and  given  serum  alone,  using  a  50  per  cent  increased  dosage. 

Pigs  from  immune  sows,  although  somewhat  resistant,  are  not 
always  free  from  the  liability  of  having  cholera.  Some  litters  may  be 
farrowed  in  infected  pens  and  go  past  weaning  time  without  becoming 
infected,  while  others  get  cholera  within  two  or  three  weeks  after 
farrowing.  The  pigs  should  be  closely  watched  and  if  any  show  signs 
of  cholera  they  should  be  given  the  serum  alone.  This  will  usually 
carry  them  well  past  weaning  time,  when  they  can  be  given  the  simul- 
taneous treatment.  If  the  herd  seems  to  be  extraordinarily  susceptible 
to  cholera,  however,  it  will  be  necessary  to  give  the  serum  alone  more 
than  once  in  order  to  carry  them  several  weeks  past  weaning.  Pigs 
given  the  simultaneous  treatment  soon  after  weaning  sometimes  lose 
this  protection  within  a  few  months.  To  acquire  a  long-time  immunity, 
pigs  should  weigh  at  least  fifty  or  sixty  pounds  at  the  time  of  receiving 
the  simultaneous  treatment.  At  this  weight  the  immunity  usually 
lasts  the  ordinary  lifetime  of  the  hog.  Certain  swine  raisers  in  this 
state  whose  herds  are  constantly  exposed  to  infection  and  who  have 
developed  a  thoroughly  immunized  lot  of  brood  sows  are  able  to  per- 
manently immunize  the  pigs  at  six  weeks  of  age  by  injecting  a  slightly 
increased  dose  of  virus  (2  c.c.)  and  a  small  dose  of  serum  (15  c.c). 


All  hogs  giving  visible  symptoms  should  be  killed  or  placed  in 
isolation  pens  without  vaccination.  It  is  a  waste  of  money  to  treat 
visibly  sick  hogs.  Notices  should  be  posted,  warning  visitors  to  keep 
out,  and  the  premises  should  be  considered  infected  for  at  least  thirty 
days  after  the  disease  has  disappeared.  Linen  posters,  14  X  n  inches, 
printed  as  follows  can  be  obtained  free  by  writing  to  the  Veterinary 
Division,  University  of  California,  Berkeley,  California: 


WARNING 

The    hogs    on    these    premises 
have    been    vaccinated    with 

VIRUS  AND  SERUM. 

No    visitors    allowed    in    these 
pens  or  fields. 


NOTICE 

The  hogs  on  these  premises  are 
free  from  cholera. 

Owners  of  infected  herds  are 

WARNED    TO   KEEP   AWAY. 

No  visitors  allowed  in  hog  pens 
or  fields  without  permission. 

Trespassers  will  be  prosecuted 
to  the  full  extent  of  the  law. 
(Signed) 


In  exposed  herds  where  no  sickness  is  present  the  use  of  the  simul- 
taneous method  is  advised.  The  vaccination  of  sows  heavy  with  pig  and 
those  having  litters  less  than  six  weeks  old  should  be  postponed  and 
such  animals  isolated  in  pens  protected  from  the  possibility  of  infection. 

Regarding  the  immunizing  of  small  pigs  against  cholera,  it  has 
already  been  mentioned  that  the  immunity  frequently  disappears  in 
from  four  to  six  months,  therefore  it  is  advisable  when  no  sickness  is 
present  to  postpone  the  vaccination  of  pigs  until  they  weigh  at  least 
fifty  pounds.  The  sows  on  which  such  pigs  are  suckling  should  not 
be  given  virus  with  serum  until  the  pigs  are  treated.  When  it  is 
deemed  necessary,  serum  alone  may  be  used  on  sows  and  their  pigs, 
but  after  an  interval  of  several  weeks  they  should  be  re-immunized 
by  the  simultaneous  method. 

The  use  of  the  so-called  double  method,  consisting  of  serum  alone, 
followed  in  ten  to  fourteen  days  with  serum  and  virus,  has  not  proved 
satisfactory  under  California  conditions.  Unless  an  interval  of  at  least 
three  weeks  is  allowed  to  elapse  between  injections  immunity  appears 
to  be  much  shorter  than  that  conferred  by  the  simultaneous  injection. 

The  information  furnished  in  this  leaflet  should  not  be  considered 
as  sufficient  to  qualify  the  average  hog  owner  to  use  serum  and  virus. 
Persons  who  desire  to  perfect  themselves  in  the  technic  of  vaccination 
so  that  they  may  vaccinate  their  own  hogs  are  advised  to  write  to  the 
Veterinary  Division  and  arrange  to  take  the  personal  instruction  which 
is  given  at  certain  times  at  the  hog  serum  laboratory.  Persons  who 
come  for  such  instruction  should  plan  to  stay  at  least  two  days. 


ANNOUNCEMENT  CONCERNING  THE  -SALE  OF  ANTI-HOG- 
CHOLERA  SERUM  AT  COST 

The  University  of  California  manufactures  anti-hog-cholera  serum 
and  is  authorized  by  act  of  the  legislature  to  sell  it  at  actual  cost 
of  production  to  any  bona  fide  resident  of  the  state  who  is  engaged  in 
hog  raising.  At  present  the  cost  is  iy2  cents  per  cubic  centimeter, 
the  same  charge  being  made  for  both  serum  and  virus.  Both  must  be 
kept  cool  and  used  as  soon  as  possible  after  being  received.  Neither 
serum  nor  virus  is  returnable  for  credit.  This  station  will  not  send, 
virus  except  for  use  by  a  qualified  man  and  then  only  in  case  hog 
cholera  exists  in  the  locality,  one  exception  to  this  being  that  for  the 
accommodation  of  breeders  who  desire  to  sell  immune  stock  or  to 
protect  hogs  which  are  sent  to  fairs  arrangements  can  be  made  to  have 
the  swine  immunized,  provided  the  work  is  done  by  a  representative 
of  this  station  and  the  owner  agrees  to  hold  the  hogs  in  strict  quaran- 
tine for  at  least  thirty  days  after  immunization. 

All  applications  should  specify  in  writing  the  amount  of  serum 
and  virus  desired  or  the  approximate  weights  of  all  hogs  to  be  treated. 
In  case  serum  is  ordered  by  telephone  or  telegraph  a  confirming  order 
signed  by  the  owner  of  the  hogs  should  be  sent  by  mail.  Serum  will 
be  shipped  only  when  cash  accompanies  the  order,  or  C.  0.  D. 

Address  all  communications  to  The  Veterinary  Division,  University 
of  California,  Berkeley,  California. 


1  «•* 

A—W-ocnj 

SISKIYOU 

u 

j 

{•§) 

_,■»-«--- 

~  7  ~ 

(A- 

/    Shasta   | 

nc-'a$-' 

\Hv 

V  _'_ . 

_1      TEHAMA 

\      t 

'-             ll- 

/   pvu 

■***  \ 

)    1 

N>  s^Aj  » 

,;,„" 

\J 

£§ 

tm 

^.«-.iW« 


^tSpJ^y-j 


On  this  map  is  indicat- 
ed the  approximate  loca- 
tion of  the  388  ranches 
on  which  the  anti-hog- 
cholera  serum  produced 
by  the  University  of  Cali- 
fornia was  used  betwe-  a 
July  1,  1914,  and  Marc.i 
31,   1915. 


